1. Field of the Invention
This invention relates to orifice fittings for measuring the flow of fluids, including oil, gas, water and slurries in pipelines. More particularly, the invention includes an eccentricity gauge and a specially designed orifice plate having a projecting hub, which orifice plate is mounted in a conventional carrier designed for insertion in a conventional orifice fitting mounted in a pipeline. Two variations of the eccentricity gauge are each designed with dowel pins sized for insertion in the respective orifice plate flow openings of various sized orifice plates and measuring the eccentricity of a path traced in the internal orifice fitting bore wall. Each eccentricity gauge is designed to measure the eccentricity of a respective orifice plate seated in an orifice fitting having an internal diameter or bore of selected size. In a first preferred embodiment of the invention the eccentricity gauge includes a dowel pin for insertion in the orifice plate flow opening, a mount carrying the dowel pin and adjustably receiving a dial indicator which is fitted with a spring-loaded indicator contact point for engaging the inside surface or wall of the orifice fitting bore and determining the eccentricity of the orifice plate mount by rotation of the eccentricity gauge in a complete circle or ellipse about the dowel pin. This test determines the concentric or off-center, perpendicular or angular position of the orifice plate with respect to the flow path through the orifice fitting. If the orifice plate is properly seated in the orifice fitting perpendicular and concentric to the flow path of the fluid, then the dial indicator will indicate little or no eccentricity in the orifice fitting mount. However, if the orifice plate is slanted or off-center with respect to the flow path in the orifice fitting, the dial indicator will measure the eccentricity of the misalignment, as hereinafter further described.
Conventional orifice fittings are designed to internally mount a carrier which receives a circular orifice plate having a flow opening of selected size to determine the pressure drop across the orifice fitting, and thus, the flow rate of a fluid flowing through a pipeline connected to the orifice fitting. Orifice plates are typically mounted in a rubber seal or O-ring seated in the fittings and are sometimes inadvertently mismounted or improperly seated with respect to the orifice fitting and the pipeline, such that the orifice plate is not perpendicular to the flow path of the fluid flowing through the pipeline or concentric with the bore of the orifice fitting. This misalignment of the orifice plate results in an error in the pressure drop readings between the upstream and downstream side of the orifice fittings and therefore results in erroneous computations of fluid flow rate through the pipeline.
Accordingly, as described above, the eccentricity gauge and orifice plate combination of this invention is designed to test the alignment of orifice plates in orifice fittings by measuring the eccentricity of the path of the eccentricity gauge contact point about the internal orifice fitting bore wall. The dowel pin of the eccentricity gauge is designed to seat in the flow opening of the orifice plate and rotates through a complete revolution with the dial indicator inside the orifice fitting, causing the contact point to traverse the internal bore wall or surface of the orifice fitting and measure the roundness or eccentricity of the path traversed by the indicator contact point. If the dial indicator element of the eccentricity gauge indicates traversal of a substantial circle by the indicator contact point, when the orifice plate is mounted in substantially perpendicular relationship with respect to the flow path of the fluid flowing through the pipeline and concentric to the bore of the orifice plate. However, if the dial indicator indicates an eccentric plate around the inside bore surface of the orifice fitting, then the orifice plate is misaligned in angular relationship or eccentric with respect to the fluid flow path and must be removed and the alignment of the orifice plate corrected inside the orifice fitting.
It is therefore an object of this invention to provide a new and improved eccentricity gauge for measuring the alignment of orifice plates in situ in orifice fittings.
Another object of the invention is to provide a new and improved hub orifice plate for insertion in conventional manner an orifice fitting and an eccentricity gauge having a dowel pin for engaging the flow opening in the hub orifice plate and rotation about the orifice plate and orifice fitting to determine the eccentricity of the measured path and therefore, the alignment of the orifice plate in the orifice fitting.
Still another object of this invention is to provide a new and improved eccentricity gauge having a dowel pin for insertion in the flow opening of an orifice plate, a dowel indicator extending from the dowel pin and fitted with an indicator contact point for contacting the inside bore surface or wall of the orifice fitting and determining the eccentricity or roundness of the path described by the indicating point when the eccentricity gauge describes a complete rotation about the dowel pin, to further determine the alignment of the orifice plate in the orifice fitting.
Yet another object of this invention is to provide an eccentricity gauge and specially designed hub orifice plate for determining the alignment of the orifice plate in an orifice fitting, which hub orifice plate is seated in the orifice fitting in conventional manner and the eccentricity gauge is positioned in the orifice fitting bore with a dowel pin inserted in the orifice plate flow opening and the indicator contact point of a dowel indicator engaging the inside bore surface of the orifice fitting, wherein complete rotation of the eccentricity gauge about the dowel pin determines the roundness or eccentricity of the path described by the indicator contact point to indicate the alignment of the orifice plate in the orifice fitting.